We all know not to stare at the sun, because it’ll fry your retina. But what about staring *near *the sun, e.g. when you’re driving and the setting sun is near your line of vision? Why doesn’t it affect the peripheral areas of your retina?
If it puts you at ease, the thickness of the atmosphere when the sun is low offers more protection than when the sun is at higher angles to the horizon. Still, one should not try to deliberately stare into the setting sun for a prolonged increment of time. When driving into the sun, the odds are high your eyes are continually scanning the road allowing no one point of the retina to be overexposed. If you are the passenger, you should try to look away.
Also, should one point of the retina in one eye be zapped, the odds are high that the exact same point in the other eye will not be zapped. (This is the theory behind strategic laser surgery on the retina, as I understand it.)
Perhaps another SD can expound upon this.
Caveat: I’ve seen demos that show how UV rays (UVA? UVB?) cannot pass through glass; yet, the light source was at an angle to the glass. Hence, this agrees with why you cannot get a suntan (or sunburn) in a car with the windows up. …But, what if the UV rays have (virtually) a normal angle of incidence to the glass? Does some UV pass through? I’ve never been convinced that it can’t happen.